/*
 * @Description  :
 * @Autor        : 杜康
 * @Date         : 2021-08-14 07:24:03 +0800
 * @LastEditors  : 杜康
 * @LastEditTime : 2021-08-14 22:14:01 +0800
 */

/**
 * @description: Base64 字符串转换
 * @param {*}
 * @return {*}
 * @author: 杜康
 * @Date: 2021-08-14 07:26:57 +0800
 */
const base64 = () => {
    let _keyStr =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    this.encode = (input) => {
        let output = "";
        let chr1, chr2, chr3, enc1, enc2, enc3, enc4;
        let i = 0;
        input = _utf8_encode(input);
        while (i < input.length) {
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);
            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;
            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }
            output =
                output +
                _keyStr.charAt(enc1) +
                _keyStr.charAt(enc2) +
                _keyStr.charAt(enc3) +
                _keyStr.charAt(enc4);
        }
        return output;
    };

    // public method for decoding
    this.decode = (input) => {
        let output = "";
        let chr1, chr2, chr3;
        let enc1, enc2, enc3, enc4;
        let i = 0;
        let c = 0;
        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
        console.log(input);
        while (i < input.length) {
            enc1 = _keyStr.indexOf(input.charAt(i++));
            enc2 = _keyStr.indexOf(input.charAt(i++));
            enc3 = _keyStr.indexOf(input.charAt(i++));
            enc4 = _keyStr.indexOf(input.charAt(i++));
            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;
            output = output + String.fromCharCode(chr1);
            if (enc3 != 64) {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64) {
                output = output + String.fromCharCode(chr3);
            }
        }
        output = _utf8_decode(output);
        return output;
    };

    // private method for UTF-8 encoding
    let _utf8_encode = (string) => {
        string = string.replace(/\r\n/g, "\n");
        let utftext = "";
        for (let n = 0; n < string.length; n++) {
            let c = string.charCodeAt(n);
            if (c < 128) {
                utftext += String.fromCharCode(c);
            } else if (c > 127 && c < 2048) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            } else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }
        }
        return utftext;
    };

    // private method for UTF-8 decoding
    let _utf8_decode = (utftext) => {
        let string = "";
        let i = 0;
        let c = 0;
        let c2 = 0;
        let c3 = 0;
        while (i < utftext.length) {
            c = utftext.charCodeAt(i);
            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            } else if (c > 191 && c < 224) {
                c2 = utftext.charCodeAt(i + 1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            } else {
                c2 = utftext.charCodeAt(i + 1);
                c3 = utftext.charCodeAt(i + 2);
                string += String.fromCharCode(
                    ((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63)
                );
                i += 3;
            }
        }
        return string;
    };
};

/**
 * @description: 将base64转换为文件
 * @param {*} dataurl
 * @param {*} filename
 * @return {*}
 * @author: 杜康
 * @Date: 2021-08-14 07:27:13 +0800
 */
const base64UrlToFile = (dataurl, filename) => {
    let arr = dataurl.split(","),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new File([u8arr], filename, { type: mime });
};

/**
 * @description: 获取文件base64编码
 * @param {*} file
 * @param {*} format 指定文件格式
 * @param {*} jpeg
 * @param {*} png
 * @param {*} gif
 * @param {*} size 指定文件大小(字节)
 * @param {*} formatMsg 格式错误提示
 * @param {*} sizeMsg 大小超出限制提示
 * @return { Promise<any> }
 * @author: 杜康
 * @Date: 2021-08-14 07:28:00 +0800
 */
const fileToBase64String = (file, format = ["jpg", "jpeg", "png", "gif"], size = 20 * 1024 * 1024, formatMsg = "文件格式不正确", sizeMsg = "文件大小超出限制") => {
    return new Promise((resolve, reject) => {
        // 格式过滤
        let suffix = file.type.split("/")[1].toLowerCase();
        let inFormat = false;
        for (let i = 0; i < format.length; i++) {
            if (suffix === format[i]) {
                inFormat = true;
                break;
            }
        }
        if (!inFormat) {
            reject(formatMsg);
        }
        // 大小过滤
        if (file.size > size) {
            reject(sizeMsg);
        }
        // 转base64字符串
        let fileReader = new FileReader();
        fileReader.readAsDataURL(file);
        fileReader.onload = () => {
            let res = fileReader.result;
            resolve({ base64String: res, suffix: suffix });
            reject("异常文件，请重新选择");
        };
    });
};

/**
 * @description: base64转blob
 * @param { base64 } base64
 * @return {*}
 * @author: 杜康
 * @Date: 2021-08-14 07:29:18 +0800
 */
const base64ToBlob = (base64) => {
    let arr = base64.split(","),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new Blob([u8arr], { type: mime });
};

/**
 * @description: 将图片转换为Base64
 * @param {*} img
 * @return {*}
 * @author: 杜康
 * @Date: 2021-08-14 07:29:41 +0800
 */
const image2Base64 = (img) => {
    let canvas = document.createElement("canvas");
    canvas.width = img.width;
    canvas.height = img.height;
    let ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0, img.width, img.height);
    let dataURL = canvas.toDataURL("image/png");
    return dataURL;
};

/**
 * @description: 获取图片Base64编码
 * @param {*} src
 * @return {*}
 * @author: 杜康
 * @Date: 2021-08-14 07:29:54 +0800
 */
const getImgBase64 = (src) => {
    let base64 = "";
    let img = new Image();
    img.src = src;
    img.onload = () => {
        base64 = image2Base64(img);
    };
};

export default {
    base64,
    base64UrlToFile,
    fileToBase64String,
    base64ToBlob,
    image2Base64,
    getImgBase64,
};
